Targeted interventions for individuals at high risk is essential for mpox control
Authors: Mingwang Shen, Hao Lai, Lei Zhang
Journal: The Lancet Infectious Diseases (2023)

Mpox, formerly known as monkeypox, is a zoonotic disease caused by an orthopoxvirus infection and is highly contagious, primarily through skin and mucosal contact.1Pan D Nazareth J Sze S et al.Transmission of monkeypox/mpox virus: a narrative review of environmental, viral, host, and population factors in relation to the 2022 international outbreak.J Med Virol. 2023; 95e28534Crossref Scopus (22) Google Scholar In July, 2022, WHO declared a global mpox outbreak as a public health emergency of international concern.2WHOWHO Director-General declares the ongoing monkeypox outbreak a public health emergency of international concern.https://www.who.int/europe/news/item/23-07-2022-who-director-general-declares-the-ongoing-monkeypox-outbreak-a-public-health-event-of-international-concernDate: July 23, 2022Date accessed: August 3, 2023Google Scholar As of July 25, 2023, mpox has affected more than 113 countries and regions, resulting in 88 600 cases and 152 deaths globally.3WHO2022–23 mpox (monkeypox) outbreak: global trends.https://worldhealthorg.shinyapps.io/mpx_global/Date: July 25, 2023Date accessed: August 3, 2023Google Scholar As a result of behavioural and medical interventions,4UK Health Security AgencyMpox (monkeypox) control: UK strategy, 2022 to 2023.https://www.gov.uk/government/publications/mpox-monkeypox-control-uk-strategy-2022-to-2023/uk-strategy-for-mpox-control-2022-to-2023Date: Dec 8, 2022Date accessed: August 3, 2023Google Scholar many countries, including the UK, the USA, and Australia, have observed a downturn in the mpox epidemics of 2022. However, mpox has begun to spread in other parts of the world, such as the Western Pacific region.3WHO2022–23 mpox (monkeypox) outbreak: global trends.https://worldhealthorg.shinyapps.io/mpx_global/Date: July 25, 2023Date accessed: August 3, 2023Google Scholar WHO emphasised ongoing surveillance, preventive measures, and research are essential to interrupt mpox transmission.5WHOMpox IHR emergency committee.https://www.who.int/groups/monkeypox-ihr-emergency-committeeDate accessed: August 3, 2023Google Scholar Experiences from previous mpox outbreaks could guide the prevention and control of the current mpox pandemic. In The Lancet Infectious Diseases, Xu-Sheng Zhang and colleagues6Zhang X-S Mandal S Mohammed H et al.Transmission dynamics and effect of control measures on the 2022 outbreak of mpox among gay, bisexual, and other men who have sex with men in England: a mathematical modelling study.Lancet Infect Dis. 2023; (published online Sept 11.)https://doi.org/10.1016/S1473-3099(23)00451-6Summary Full Text Full Text PDF Scopus (11) Google Scholar used a mathematical model to investigate the transmission dynamics of the 2022 mpox outbreak among gay, bisexual, and other men who have sex with men (GBMSM) in England, with the aim of evaluating the effects of implemented control measures on the mpox epidemic. Building the model on detailed data, covering sexual behaviour, epidemiological, and intervention data, the study demonstrated a reduction in the median serial interval from 10·71 days (IQR 5·50–45·42) in May, 2022, to 4·77 days (1·88–26·55) in August, 2022. This suggests a slowing down in transmission of mpox among GBMSM. The study identified GBMSM with high-risk behaviours to be most affected by the mpox outbreak and transmission in England, and the decline in reported cases might be due to the decrease in sexual contact among GBMSM, alongside the shortening effective infectious period from 3·0 to 2·4 days. The study also showed that although the targeted vaccination of GBMSM at high risk of mpox had a limited effect in controlling the epidemic due to delayed coverage, vaccination strategies were of utmost importance in preventing a potential resurgence of the outbreak. Behavioural changes played a key role in reducing mpox transmission in England. Over 80% of the transmission of mpox was estimated to result from GBMSM with high-risk behaviours, or resulted from contact with members of this group. Short-term voluntary reduction in high-risk behaviours, reducing the number of sexual partners and sexual encounters, substantially reduced the risk of acquisition and further transmission of mpox. Identifying GBMSM who are at high risk of sexually transmitted infections would be essential for targeted behavioural intervention. Recent developments have seen the application of artificial intelligence to determine the risk of sexually transmitted infections in GBMSM in high-income countries.7Bao Y Medland NA Fairley CK et al.Predicting the diagnosis of HIV and sexually transmitted infections among men who have sex with men using machine learning approaches.J Infect. 2021; 82: 48-59Summary Full Text Full Text PDF PubMed Scopus (26) Google Scholar This latest advancement might enable precision prevention of mpox at a population level. In particular, the identification of individuals at high risk in sexual contact networks would enable early prevention of super-spreading events. Biomedical interventions, such as vaccination, had little effect on the initial downturn of the mpox outbreak in England, due to their delayed implementation. Zhang and colleagues have shown that vaccination is highly effective in preventing monkeypox virus infection, and starting vaccination 2 weeks into an outbreak could have averted 2·5 times more infections than the effects seen with later implementation.6Zhang X-S Mandal S Mohammed H et al.Transmission dynamics and effect of control measures on the 2022 outbreak of mpox among gay, bisexual, and other men who have sex with men in England: a mathematical modelling study.Lancet Infect Dis. 2023; (published online Sept 11.)https://doi.org/10.1016/S1473-3099(23)00451-6Summary Full Text Full Text PDF Scopus (11) Google Scholar Policymakers in England had low vaccine stock, and were unprepared for the mpox outbreak. As a result, resource allocation for mpox vaccines should balance the potential disease and economic burdens of future outbreaks and the cost of vaccine supply and storage (appendix). Stocking a sizeable quantity of vaccines for timely vaccination could reduce the scale of outbreaks and subsequent cost of treatment, but might represent an ongoing economic burden of vaccine retainment. Cold chain conditions, with storage temperatures of –20°C to –80°C, and chain of custody during the entire shelf life of the vaccine (3–9 years, depending on storage temperature) both have substantial financial costs.8Government of CanadaImvamune: storage temperatures, shelf life, shipment and supportive temperature excursion information.https://www.canada.ca/en/public-health/services/diseases/mpox/technical-documents/imvamune-storage-temperatures-shelf-life-shipment-temperature-excursion.html#fn*-rfDate: May 19, 2023Date accessed: August 3, 2023Google Scholar Conversely, low vaccine storage would not be sufficient to curtail the transmission of mpox in the case of an outbreak. Therefore, monitoring real-time data on mpox incidence, estimating the virulence of prevalent monkeypox virus clades, and projecting the epidemic trend is necessary for the health-care system to develop dynamic vaccine allocation and cost-effective vaccination strategies. Future research should focus on determining the number of vaccine doses required to balance the harm of potential outbreaks and the budget for maintaining an effective stock of vaccines. Overall, this study highlights the importance of both early behavioural intervention and vaccination initiation in mpox control. The key message of this study echoes WHO's recommendations, that modification of risk behaviours, prompt diagnosis, and isolation will be crucial in reducing mpox transmission in the population, including in low-income countries.9WHOFifth meeting of the International Health Regulations (2005) (IHR) emergency committee on the multi-country outbreak of mpox (monkeypox).https://www.who.int/news/item/11-05-2023-fifth-meeting-of-the-international-health-regulations-%282005%29-%28ihr%29-emergency-committee-on-the-multi-country-outbreak-of-monkeypox-%28Mpox%29Date: May 11, 2023Date accessed: August 3, 2023Google Scholar Early and widespread vaccination could play a significant role in preventing the reoccurrence of mpox. We declare no competing interests. Download .pdf (.27 MB) Help with pdf files Supplementary appendix Transmission dynamics and effect of control measures on the 2022 outbreak of mpox among gay, bisexual, and other men who have sex with men in England: a mathematical modelling studyThe mpox outbreak in England probably resulted from high sexual partner rates among some GBMSM, with reductions in partner rates reversing the outbreak, and with vaccination minimising future outbreaks. Full-Text PDF Open Access